<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        p.demo
        {
            margin-left: 2cm;
        }
    </style>
</head>
<body>
<p>
    A no
</p>
<p class="demo">
    2dm margin
</p>
<p>
    a other text to mragin
</p>
</body>
</html>